The only way to know the composition of drought-stressed corn silage is to have it tested, points out Joe Lauer, University of Wisconsin extension corn agronomist.

Lauer says droughty corn silage usually has more sugar and crude protein than normal silage. Drought reduces grain yield, resulting in higher fiber levels. It usually lowers lignin production, too, which increases fiber digestibility. However, when dry weather comes at the end of the season, grain yield may be reduced, but the stalks are large and well-lignified, so fiber digestibility isn’t increased.

Lauer says the energy value of droughty corn silage is usually lower than that of normal silage, but not as low is it appears based on grain content.

If drought-stressed corn is ensiled at the proper moisture content, and other steps are followed to ensure good fermentation, nitrate testing shouldn’t be necessary. That’s because nitrate concentration usually declines by one-third to one-half during fermentation.

"However, it’s prudent to follow precautions regarding dangers of nitrate toxicity to livestock, especially with grazing and green-chopping, and dangers of silo gasses to humans when dealing with drought-stressed corn," says Lauer.